Abstract The nicotine delivery profile of oral nicotine pouches (NPs) affects their abuse liability and ability to function as alternatives for users of riskier combustible products. However, it is unclear if flavors exert any effect on nicotine pharmacology. Here, data from two open-label, randomized, nine-way cross-over, single dose administration pharmacokinetic (PK) and pharmacodynamic (PD) studies of unflavored and flavored varieties of a dry 6 mg nicotine and a moist 9 mg nicotine NP product was analyzed. Maximum plasma concentrations of nicotine (Cmax) were observed ~ 1 h after NP administration, with overlapping mean values for the two products (13.02–15.95 ng/mL). The total nicotine exposure (AUCinf) was 44.65–54.53 h*ng/mL. Equivalence testing for AUCinf and Cmax between unflavored and flavored NP varieties showed equivalence for all varieties except NP moist D minty and NP moist H minty compared to NP moist A unflavored. Neither AUCinf, Cmax, or time to maximum nicotine concentration were affected by flavor. The effect of flavor was more pronounced for the moist product, where subjects rated the flavored varieties higher for satisfaction, product-liking, and intent to use again. Overall, large variations were seen between subjects in terms of flavor preferences, highlighting the requirement for multiple varieties and products.

INTRODUCTION:The single-dose pharmacokinetics (PK) of a novel, non-tobacco-based nicotine pouch, ZYN, 3 and 6 mg, were compared with 8 mg General snus (part 1) and ZYN 8 mg was compared with 18 mg Longhorn moist snuff (part 2). The present study demonstrates the characteristics of three strengths of a novel tobacco-free oral snus, ZYN, viz. the extraction of nicotine from the oral cavity and its uptake into the systemic blood circulation. Comparison is made to Swedish General snus and American Longhorn moist snuff and from literature 4 mg Nicorette gum and mean of 13 brands of e-cigarettes.AIMS AND METHODS:A single-dose randomized crossover design was used. In vivo extraction and PK parameters were determined.RESULTS:Part 1. The AUCinf of ZYN 3 mg was 27% smaller than that of 8 mg General and the AUCinf of ZYN 6 mg was 34% larger than that of 8 mg General. Less nicotine was extracted from ZYN 3 mg (1.5 mg) and more from ZYN 6 mg (3.5 mg) than from 8 mg General (2.4 mg). The extracted fractions of nicotine for both ZYN products (56% and 59%) were significantly larger than for 8 mg General (32%).RESULTS:Part 2. Close to identical plasma nicotine curves, AUCinf and Cmax were found for ZYN 8 mg and Longhorn Natural 18 mg moist snuff. The extracted amount of nicotine from ZYN 8 mg (3.8 mg) was larger than the amount extracted from Longhorn Natural 18 mg (3.0 mg), but smaller than the extracted amount of nicotine from General 2 × 8 mg snus pouches (5.0 mg). The extracted fraction of nicotine for ZYN 8 mg (50%) was larger than for Longhorn Natural (19%) and General 2 × 8 mg snus pouches (33%).CONCLUSIONS:The two higher doses of ZYN (6 and 8 mg) deliver nicotine as quickly and to a similar extent as existing smokeless products, with no significant adverse effects.

Structural analysis of carbohydrates is a complicated endeavour, due to the complexity and diversity of the samples at hand. Herein, we apply a combined computational and experimental approach, employing molecular dynamics (MD) and density functional theory (DFT) calculations together with NMR and Raman optical activity (ROA) measurements, in the structural study of three mannobiose disaccharides, consisting of two mannoses with varying glycosidic linkages. The disaccharide structures make up the scaffold of high mannose glycans and are therefore important targets for structural analysis. Based on the MD population analysis and NMR, the major conformers of each mannobiose were identified and used as input for DFT analysis. By systematically varying the solvent models used to describe water interacting with the molecules and applying overlap integral analysis to the resulting calculational ROA spectra, we found that a full quantum mechanical/molecular mechanical approach is required for an optimal calculation of the ROA parameters. Subsequent normal mode analysis of the predicted vibrational modes was attempted in order to identify possible marker bands for glycosidic linkages. However, the normal mode vibrations of the mannobioses are completely delocalised, presumably due to conformational flexibility in these compounds, rendering the identification of isolated marker bands unfeasible.

At the catalytic site for the hydrolysis of cellulose the enzyme cellobiohydrolase Cel7A binds the enantiomers of the adrenergic beta-blocker propranolol with different selectivity. Methyl-to-hydroxymethyl group modifications of propranolol, which result in higher affinity and improved selectivity, were herein studied by 1 H,1 H and 1 H,13 C scalar spin-spin coupling constants as well as utilizing the nuclear Overhauser effect (NOE) in conjunction with molecular dynamics simulations of the ligands per se, which showed the presence of all-antiperiplanar conformations, except for the one containing a vicinal oxygen-oxygen arrangement governed by the gauche effect. For the ligand-protein complexes investigated by NMR spectroscopy using, inter alia, transferred NOESY and saturation-transfer difference (STD) NMR experiments the S-isomers were shown to bind with a higher affinity and a conformation similar to that preferred in solution, in contrast to the R-isomer. The fact that the S-form of the propranolol enantiomer is pre-arranged for binding to the protein is also observed for a crystal structure of dihydroxy-(S)-propranolol and Cel7A presented herein. Whereas the binding of propranolol is entropy driven, the complexation with the dihydroxy analogue is anticipated to be favored also by an enthalpic term, such as for its enantiomer, that is, dihydroxy-(R)-propranolol, because hydrogen-bond donation replaces the corresponding bonding from hydroxyl groups in glucosyl residues of the natural substrate. In addition to a favorable entropy component, albeit lesser in magnitude, this represents an effect of enthalpy-to-entropy compensation in ligand-protein interactions.

A series of compounds associated with naturally occurring and biologically relevant glycans consisting of α-mannosides were prepared and analyzed using collision-induced dissociation (CID), energy-resolved mass spectrometry (ERMS), and 1H nuclear magnetic resonance spectroscopy. The CID experiments of sodiated species of disaccharides and ERMS experiments revealed that the order of stability of mannosyl linkages was as follows: 6-linked > 4-linked ≧ 2-linked > 3-linked mannosyl residues. Analysis of linear trisaccharides revealed that the order observed in disaccharides could be applied to higher glycans. A branched trisaccharide showed a distinct dissociation pattern with two constituting disaccharide ions. The estimation of the content of this ion mixture was possible using the disaccharide spectra. The hydrolysis of mannose linkages at 3- and 6-positions in the branched trisaccharide revealed that the 3-linkage was cleaved twice as fast as the 6-linkage. It was observed that the solution-phase hydrolysis and gas-phase dissociation have similar energetics.

Pd-catalyzed C-C bond-forming reactions under oxidative conditions constitute a class of important and widely used synthetic protocols. This Article describes a mechanistic investigation of the arylating carbocyclization of allenynes using boronic acids and focuses on the correlation between reaction conditions and product selectivity. Isotope effects confirm that either allenic or propargylic C-H activation occurs directly after substrate binding. With an excess of H2O, a triene product is selectively formed via allenic C-H activation. The latter C-H activation was found to be turnover-limiting and the reaction zeroth order in reactants as well as the oxidant. A dominant feature is continuous catalyst activation, which was shown to occur even in the absence of substrate. Smaller amounts of H2O lead to mixtures of triene and vinylallene products, where the latter is formed via propargylic C-H activation. The formation of triene occurs only in the presence of ArB(OH)2. Vinylallene, on the other hand, was shown to be formed by consumption of (ArBO)3 as a first-order reactant. Conditions with sub-stoichiometric BF3·OEt2 gave selectively the vinylallene product, and the reaction is first order in PhB(OH)2. Both C-H activation and transmetalation influence the reaction rate. However, with electron-deficient ArB(OH)2, C-H activation is turnover-limiting. It was difficult to establish the order of transmetalation vs C-H activation with certainty, but the results suggest that BF3·OEt2 promotes an early transmetalation. The catalytically active species were found to be dependent on the reaction conditions, and H2O is a crucial parameter in the control of selectivity.

The monosaccharide L-rhamnose is common in bacterial polysaccharides and the disaccharide α-L-Rhap-α-(1 → 2)-α-L-Rhap-OMe represents a structural model for a part of Shigella flexneri O-antigen polysaccharides. Utilization of [1'-(13)C]-site-specific labeling in the anomeric position at the glycosidic linkage between the two sugar residues facilitated the determination of transglycosidic NMR (3)JCH and (3)JCC coupling constants. Based on these spin-spin couplings the major state and the conformational distribution could be determined with respect to the ψ torsion angle, which changed between water and dimethyl sulfoxide (DMSO) as solvents, a finding mirrored by molecular dynamics (MD) simulations with explicit solvent molecules. The (13)C NMR spin relaxation parameters T1, T2, and heteronuclear NOE of the probe were measured for the disaccharide in DMSO-d6 at two magnetic field strengths, with standard deviations ≤1%. The combination of MD simulation and a stochastic description based on the diffusive chain model resulted in excellent agreement between calculated and experimentally observed (13)C relaxation parameters, with an average error of <2%. The coupling between the global reorientation of the molecule and the local motion of the spin probe is deemed essential if reproduction of NMR relaxation parameters should succeed, since decoupling of the two modes of motion results in significantly worse agreement. Calculation of (13)C relaxation parameters based on the correlation functions obtained directly from the MD simulation of the solute molecule in DMSO as solvent showed satisfactory agreement with errors on the order of 10% or less.

Highly selective protocols for the carbocyclization/arylation of allenynes using arylboronic acids are reported. Arylated vinylallenes are obtained with the use of BF 3 ⋅Et 2 O as an additive, whereas addition of water leads to arylated trienes. These conditions provide the respective products with excellent selectivities (generally >97:3) for a range of boronic acids and different allenynes. It has been revealed that water plays a crucial role for the product distribution.

In the title compound, C14H20O5, an intermediate in the synthesis of oligosaccharides, the glycosidic [H—C—O—C(H3)] torsion angle φHis 52.3° and theexo-cyclic [H—C—O—C(H2)] torsion angle θHis −11.7°. The hexapyranose ring has a chair conformation. In the crystal, molecules are linked by O—H...O hydrogen bonds, forming chains propagating along [010]. Enclosed within the chains areR33(12) ring motifs involving three molecules. The chains are linkedviaC—H...π interactions, forming a three-dimensional network.

Room temperature ionic liquids (ILs) of the imidazolium family have attracted much attention during the past decade for their capability to dissolve biomass. Besides experimental work, numerous compuational studies have been concerned with the physical properties of both neat ILs and their interactions with different solutes, in particular, carbohydrates. Many classical force fields designed specifically for ILs have been found to yield viscosities that are too high for the liquid state, which has been attributed to the fact that the effective charge densities are too high due to the lack of electronic polarizability. One solution to this problem has been uniform scaling of the partial charges by a scale factor in the range 0.6-0.9, depending on model. This procedure has been shown to improve the viscosity of the models, and also to positively affect other properties, such as diffusion constants and ionic conductivity. However, less attention has been paid to how this affects the overall thermodynamics of the system, and the problems it might create when the IL models are combined with other force fields (e.g., for solutes). In the present work, we employ three widely used IL force fields to simulate 1-n-butyl-3-methyl-imidazolium chloride in both the crystal and the liquid state, as well as its binary mixture with ethanol. Two approaches are used: one in which the ionic charge is retained at its full integer value and one in which the partial charges are uniformly reduced to 85%. We investigate and calculate crystal and liquid structures, molar heat capacities, heats of fusion, self-diffusion constants, ionic conductivity, and viscosity for the neat IL, and ethanol activity as a function of ethanol concentration for the binary mixture. We show that properties of the crystal are less affected by charge scaling compared to the liquid. In the liquid state, transport properties of the neat IL are generally improved by scaling, whereas values for the heat of fusion are unaffected, and results for the heat capacity are ambiguous. Neither full nor reduced charges could reproduce experimental ethanol activities for the whole range of compositions.

Conformational sampling for a set of 10 α- or β-(1→6)-linked oligosaccharides has been studied using explicit solvent Hamiltonian replica exchange (HREX) simulations and NMR spectroscopy techniques. Validation of the force field and simulation methodology is done by comparing calculated transglycosidic J coupling constants and proton-proton distances with the corresponding NMR data. Initial calculations showed poor agreement, for example, with >3 Hz deviation of the calculated (3)J(H5,H6R) values from the experimental data, prompting optimization of the ω torsion angle parameters associated with (1→6)-linkages. The resulting force field is in overall good agreement (i.e., within ∼0.5 Hz deviation) from experimental (3)J(H5,H6R) values, although some small limitations are evident. Detailed hydrogen bonding analysis indicates that most of the compounds lack direct intramolecular H-bonds between the two monosaccharides; however, minor sampling of the O6···HO2' hydrogen bond is present in three compounds. The results verify the role of the gauche effect between O5 and O6 atoms in gluco- and manno-configured pyranosides causing the ω torsion angle to sample an equilibrium between the gt and gg rotamers. Conversely, galacto-configured pyranosides sample a population distribution in equilibrium between gt and tg rotamers, while the gg rotamer populations are minor. Water radial distribution functions suggest decreased accessibility to the O6 atom in the (1→6)-linkage as compared to the O6' atom in the nonreducing sugar. The role of bridging water molecules between two sugar moieties on the distributions of ω torsion angles in oligosaccharides is also explored.

Site‐specific 13C isotope labeling is a useful approach that allows for the measurement of homonuclear 13C,13C coupling constants. For three site‐specifically labeled oligosaccharides, it is demonstrated that using the J‐HMBC experiment for measuring heteronuclear long‐range coupling constants is problematical for the carbons adjacent to the spin label. By incorporating either a selective inversion pulse or a constant‐time element in the pulse sequence, the interference from one‐bond 13C,13C scalar couplings is suppressed, allowing the coupling constants of interest to be measured without complications. Experimental spectra are compared with spectra of a nonlabeled compound as well as with simulated spectra. The work extends the use of the J‐HMBC experiments to site‐specifically labeled molecules, thereby increasing the number of coupling constants that can be obtained from a single preparation of a molecule. Copyright © 2014 John Wiley & Sons, Ltd.

Raman and Raman optical activity (ROA) spectroscopy are used to study the solution-phase structure of the glycan moiety of the protein ribonuclease B (RNase B). Spectral data of the intact glycan moiety of RNase B is obtained by subtracting high-quality spectral data of RNase A, the non-glycosylated form of the RNase, from the spectra of the glycoprotein. The remaining difference spectra are compared to spectra generated from Raman and ROA data of the constituent disaccharides of the RNase glycan, achieving convincing spectral overlap. The results show that ROA spectroscopy is able to extract detailed spectral data of the glycan moieties of proteins, provided that the non-glycosylated isoform is available. Furthermore, good comparison between the full glycan spectrum and the regenerated spectra based on the disaccharide data lends great promise to ROA as a tool for the solution-phase structural analysis of this structurally elusive class of biomolecules.

The conformational preferences of several oligosaccharides are investigated herein using a combination of NMR spectroscopy and molecular dynamics (MD) simulations, focusing on the torsion angles as ...

A combination of solid-state (13)C NMR tensor data and DFT computational methods is utilized to predict the conformation in disordered methyl α-L-rhamnofuranoside. This previously uncharacterized solid is found to be crystalline and consists of at least six distinct conformations that exchange on the kHz time scale. A total of 66 model structures were evaluated, and six were identified as being consistent with experimental (13)C NMR data. All feasible structures have very similar carbon and oxygen positions and differ most significantly in OH hydrogen orientations. A concerted rearrangement of OH hydrogens is proposed to account for the observed dynamic disorder. This rearrangement is accompanied by smaller changes in ring conformation and is slow enough to be observed on the NMR time scale due to severe steric crowding among ring substituents. The relatively minor differences in non-hydrogen atom positions in the final structures suggest that characterization of a complete crystal structure by X-ray powder diffraction may be feasible.

1H and 13C NMR chemical shift data are used by the computer program CASPER to predict chemical shifts of oligo- and polysaccharides. Three types of data are used, namely, those from monosaccharides, disaccharides, and trisaccharides. To improve the accuracy of these predictions we have assigned the 1H and 13C NMR chemical shifts of eleven monosaccharides, eleven disaccharides, twenty trisaccharides, and one tetrasaccharide; in total 43 compounds. Five of the oligosaccharides gave two distinct sets of NMR resonances due to the α- and β-anomeric forms resulting in 48 1H and 13C NMR chemical shift data sets. In addition, the pyranose ring forms of Neu5Ac were assigned at two temperatures, due to chemical shift displacements as a function of temperature. The 1H NMR chemical shifts were refined using total line-shape analysis with the PERCH NMR software. 1H and 13C NMR chemical shift predictions were subsequently carried out by the CASPER program (http://www.casper.organ.su.se/casper/) for three branched oligosaccharides having different functional groups at their reducing ends, namely, a mannose-containing pentasaccharide, and two fucose-containing heptasaccharides having N-acetyllactosamine residues in the backbone of their structures. Good to excellent agreement was observed between predicted and experimental 1H and 13C NMR chemical shifts showing the utility of the method for structural determination or confirmation of synthesized oligosaccharides.

The intrinsic flexibility of carbohydrates facilitates different 3D structures in response to altered environments. At glycosidic (1 -> 46)-linkages, three torsion angles are variable, and herein the conformation and dynamics of beta-1.-Fucp-(1 -> 6)-alpha-D-Glcp-OMe are investigated using a combination of NMR spectroscopy and molecular dynamics (MD) simulations. The disaccharide shows evidence of conformational averaging for the psi and co torsion angles, best explained by a four-state conformational distribution. Notably, there is a significant population of conformations having psi = 85 degrees (clinal) in addition to those having psi = 180 degrees (anfiperiplanar). Moderate differences in C-13 R-1 relaxation rates are found to be best explained by axially symmetric tumbling in combination with minor differences in librational motion for the two residues, whereas the isomerization motions are occurring too slowly to significantly to the observed relaxation rates. The MD simulation was found to give a reasonably good agreement with experiment, especially with respect to diffusive properties, among which the rotational anisotropy, D parallel to/D parallel to, is found to be 2.35. The force field employed showed too narrow omega torsion angles in the gauche trans and gauche gauche states as well as overestimating the population of the gauche trans conformer. This information can subsequently be used in directing parameter developments and emphasizes the need for refinement of force fields for (1 -> 6)-linked carbohydrates.

Glycan structural information is a prerequisite for elucidation of carbohydrate function in biological systems. To this end we employ a tripod approach for investigation of carbohydrate 3D structure and dynamics based on organic synthesis; different experimental spectroscopy techniques, NMR being of prime importance; and molecular simulations using, in particular, molecular dynamics (MD) simulations. The synthesis of oligosaccharides in the form of glucosyl fluorides is described, and their use as substrates for the Lam16A E115S glucosyl synthase is exemplified as well as a conformational analysis of a cyclic β-(1→3)-heptaglucan based on molecular simulations. The flexibility of the N -acetyl group of aminosugars is by MD simulations indicated to function as a gatekeeper for transitions of glycosidic torsion angles to other regions of conformational space. A novel approach to visualize glycoprotein (GP) structures is presented in which the protein is shown by, for example, ribbons, but instead of stick or space-filling models for the carbohydrate portion it is visualized by the colored geometrical figures known as CFG representation in a 3D way, which we denote 3D-CFG, thereby effectively highlighting the sugar residues of the glycan part of the GP and the position(s) on the protein.